{
 "generated_utc": "2026-08-16T17:27:01Z",
 "gfs_cycle_utc": "2026-08-16T12:00:00Z",
 "model": {
  "source": "NCEP GFS 0.50 degree",
  "vertical_coordinate": "constant density (isopycnic)",
  "horizon_hours": 463.5,
  "output_interval_min": 30,
  "integration_step_s": 900,
  "wind_field_interval_h": 3
 },
 "staleness": {
  "fresh_seed_max_h": 24.0,
  "served_until_h": 336.0,
  "track_max_age_h": 72.0,
  "region_spread_deg": 60.0,
  "note": "A trajectory is served for 336 h after the last real fix and then the flight disappears. That matches the archive's own bridging limit: 23% of flights go quiet for over a week and are then heard again, so a shorter window drops balloons that are still flying. Past dead_reckoned flights the balloon has not been heard from since seed_time, so its present position is a prediction too -- the silent period is reconstructed from GFS analyses of weather that has already happened, which is why wind_source distinguishes analysis from forecast. Use display_as, not seed_age_h, to decide how to draw a flight: 'track' means the members still agree and a line is meaningful, 'region' means draw the member envelope instead because the nominal member is no better than any other."
 },
 "members": {
  "offsets_m": [
   -2000,
   -1500,
   -1000,
   -500,
   0,
   500,
   1000,
   1500,
   2000
  ],
  "nominal_offset_m": 0,
  "note": "Each member is seeded at the last observed altitude plus its offset and then conserves the density it started with. The ladder is a sensitivity fan, not a probability distribution: adjacent members diverge by roughly 1,200 km over seven days. levels_spanned reports how many GFS levels the fan actually straddles, usually 2 or 3."
 },
 "files": {
  "trajectories_csv_gz": "PBA_forecast_20260816_12Z.csv.gz",
  "trajectories_geojson_gz": "PBA_forecast_20260816_12Z.geojson.gz"
 },
 "counts": {
  "flights": 24,
  "members": 9,
  "rows": 92106
 },
 "flights": [
  {
   "callsign": "AG6NS-23",
   "flight_id": "AG6NS-23_2026-02-07",
   "payload_type": "WSPR",
   "seed_time": "2026-08-16 11:53:40",
   "seed_lat": -55.79167,
   "seed_lon": 64.62501,
   "seed_alt_m": 12300.0,
   "seed_age_h": 5.44,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-23 11:30:00",
    "lat": -54.31986,
    "lon": 83.4579,
    "alt_m": 12366.1
   },
   "member_spread_deg": {
    "lat": 5.32,
    "lon": 10.87
   },
   "member_spread_now_deg": {
    "lat": 1.41,
    "lon": 2.32
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "BSS53",
   "flight_id": "BSS53_2026-03-09",
   "payload_type": "WSPR",
   "seed_time": "2026-08-16 09:13:48",
   "seed_lat": 53.125,
   "seed_lon": 92.70833,
   "seed_alt_m": 12740.0,
   "seed_age_h": 8.1,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-23 11:45:00",
    "lat": 82.99714,
    "lon": 119.28234,
    "alt_m": 12176.8
   },
   "member_spread_deg": {
    "lat": 49.48,
    "lon": 298.42
   },
   "member_spread_now_deg": {
    "lat": 0.92,
    "lon": 6.5
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "BSS54",
   "flight_id": "BSS54_2026-07-09",
   "payload_type": "WSPR",
   "seed_time": "2026-08-15 23:28:18",
   "seed_lat": 48.02083,
   "seed_lon": 165.79167,
   "seed_alt_m": 14140.0,
   "seed_age_h": 17.86,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-08-23 11:30:00",
    "lat": 43.02302,
    "lon": -79.09065,
    "alt_m": 13855.1
   },
   "member_spread_deg": {
    "lat": 28.66,
    "lon": 115.95
   },
   "member_spread_now_deg": {
    "lat": 1.3,
    "lon": 4.02
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DG2GG-23",
   "flight_id": "DG2GG-23_2026-05-23",
   "payload_type": "WSPR",
   "seed_time": "2026-08-16 10:09:00",
   "seed_lat": 43.29167,
   "seed_lon": 30.625,
   "seed_alt_m": 12660.0,
   "seed_age_h": 7.18,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-23 11:45:00",
    "lat": 38.90422,
    "lon": -154.16013,
    "alt_m": 12904.5
   },
   "member_spread_deg": {
    "lat": 48.98,
    "lon": 312.62
   },
   "member_spread_now_deg": {
    "lat": 1.76,
    "lon": 3.27
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DG2GG-27",
   "flight_id": "DG2GG-27_2026-07-04",
   "payload_type": "WSPR",
   "seed_time": "2026-08-10 00:18:00",
   "seed_lat": 17.10417,
   "seed_lon": -113.33333,
   "seed_alt_m": 14010.0,
   "seed_age_h": 161.03,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-08-23 11:45:00",
    "lat": 16.09521,
    "lon": -62.36435,
    "alt_m": 14035.5
   },
   "member_spread_deg": {
    "lat": 38.07,
    "lon": 142.21
   },
   "member_spread_now_deg": {
    "lat": 33.82,
    "lon": 80.7
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "DG2GG-29",
   "flight_id": "DG2GG-29_2026-07-28",
   "payload_type": "WSPR",
   "seed_time": "2026-08-04 04:57:00",
   "seed_lat": 46.91667,
   "seed_lon": 165.25,
   "seed_alt_m": 13380.0,
   "seed_age_h": 300.38,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-23 11:30:00",
    "lat": 37.59307,
    "lon": 74.39601,
    "alt_m": 13364.4
   },
   "member_spread_deg": {
    "lat": 83.09,
    "lon": 309.15
   },
   "member_spread_now_deg": {
    "lat": 68.64,
    "lon": 208.48
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "DG2GG-30",
   "flight_id": "DG2GG-30_2026-08-07",
   "payload_type": "WSPR",
   "seed_time": "2026-08-16 16:06:00",
   "seed_lat": 47.95833,
   "seed_lon": -114.70833,
   "seed_alt_m": 12820.0,
   "seed_age_h": 1.23,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-23 15:30:00",
    "lat": 53.09447,
    "lon": 99.84907,
    "alt_m": 12578.9
   },
   "member_spread_deg": {
    "lat": 13.32,
    "lon": 68.3
   },
   "member_spread_now_deg": {
    "lat": 0.1,
    "lon": 0.1
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DG2GG-31",
   "flight_id": "DG2GG-31_2026-08-13",
   "payload_type": "WSPR",
   "seed_time": "2026-08-16 12:32:00",
   "seed_lat": 40.41667,
   "seed_lon": 26.29167,
   "seed_alt_m": 13180.0,
   "seed_age_h": 4.8,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-23 12:00:00",
    "lat": 48.703,
    "lon": -172.5817,
    "alt_m": 13351.6
   },
   "member_spread_deg": {
    "lat": 39.36,
    "lon": 41.31
   },
   "member_spread_now_deg": {
    "lat": 0.93,
    "lon": 1.32
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DN3LEO-13",
   "flight_id": "DN3LEO-13_2026-04-12",
   "payload_type": "WSPR",
   "seed_time": "2026-08-16 15:08:00",
   "seed_lat": 87.9375,
   "seed_lon": -118.41667,
   "seed_alt_m": 11770.0,
   "seed_age_h": 2.2,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-23 14:45:00",
    "lat": 63.00942,
    "lon": 137.96035,
    "alt_m": 11970.1
   },
   "member_spread_deg": {
    "lat": 25.33,
    "lon": 346.16
   },
   "member_spread_now_deg": {
    "lat": 0.37,
    "lon": 20.52
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "EI6BFW-18",
   "flight_id": "EI6BFW-18_2026-07-25",
   "payload_type": "WSPR",
   "seed_time": "2026-08-16 16:48:00",
   "seed_lat": 59.375,
   "seed_lon": -83.54167,
   "seed_alt_m": 12560.0,
   "seed_age_h": 0.53,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-23 16:45:00",
    "lat": 61.90185,
    "lon": 39.4791,
    "alt_m": 12448.5
   },
   "member_spread_deg": {
    "lat": 27.19,
    "lon": 127.12
   },
   "member_spread_now_deg": {
    "lat": 0.05,
    "lon": 0.16
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "GSN-TS",
   "flight_id": "GSN-TS_2026-08-15",
   "payload_type": "OTHER",
   "seed_time": "2026-08-16 01:30:23",
   "seed_lat": 53.81866,
   "seed_lon": 16.61656,
   "seed_alt_m": 9972.0,
   "seed_age_h": 15.83,
   "float_reliable": false,
   "dead_reckoned": false,
   "levels_spanned": 4,
   "nominal_end": {
    "valid_time": "2026-08-23 11:30:00",
    "lat": 78.42098,
    "lon": -140.02128,
    "alt_m": 9765.2
   },
   "member_spread_deg": {
    "lat": 47.01,
    "lon": 308.96
   },
   "member_spread_now_deg": {
    "lat": 4.57,
    "lon": 5.07
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "K5NOT-11",
   "flight_id": "K5NOT-11_2026-06-20",
   "payload_type": "WSPR",
   "seed_time": "2026-08-15 20:50:37",
   "seed_lat": 40.97911,
   "seed_lon": -75.41666,
   "seed_alt_m": 13300.0,
   "seed_age_h": 20.49,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-23 11:45:00",
    "lat": 19.46939,
    "lon": -91.21591,
    "alt_m": 13344.5
   },
   "member_spread_deg": {
    "lat": 15.71,
    "lon": 73.73
   },
   "member_spread_now_deg": {
    "lat": 2.02,
    "lon": 9.08
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KC3LBR-449",
   "flight_id": "KC3LBR-449_2026-07-06",
   "payload_type": "WSPR",
   "seed_time": "2026-08-16 15:13:33",
   "seed_lat": 63.3125,
   "seed_lon": 70.5,
   "seed_alt_m": 13340.0,
   "seed_age_h": 2.11,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-23 14:45:00",
    "lat": 64.04432,
    "lon": 129.83703,
    "alt_m": 13084.2
   },
   "member_spread_deg": {
    "lat": 6.4,
    "lon": 296.31
   },
   "member_spread_now_deg": {
    "lat": 0.11,
    "lon": 0.38
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KC5TRB-1",
   "flight_id": "KC5TRB-1_2026-06-20",
   "payload_type": "WSPR",
   "seed_time": "2026-08-12 11:40:43",
   "seed_lat": 57.39578,
   "seed_lon": 26.00003,
   "seed_alt_m": 12570.0,
   "seed_age_h": 101.66,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-23 11:45:00",
    "lat": 64.34257,
    "lon": 78.23211,
    "alt_m": 12602.6
   },
   "member_spread_deg": {
    "lat": 22.34,
    "lon": 216.06
   },
   "member_spread_now_deg": {
    "lat": 27.76,
    "lon": 266.7
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "KD7FXO-1",
   "flight_id": "KD7FXO-1_2026-08-02",
   "payload_type": "WSPR",
   "seed_time": "2026-08-16 13:50:00",
   "seed_lat": 47.77083,
   "seed_lon": 57.0,
   "seed_alt_m": 12500.0,
   "seed_age_h": 3.5,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-23 13:15:00",
    "lat": 40.58624,
    "lon": -132.51483,
    "alt_m": 12921.8
   },
   "member_spread_deg": {
    "lat": 24.51,
    "lon": 345.64
   },
   "member_spread_now_deg": {
    "lat": 0.36,
    "lon": 2.0
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KE8RES-8",
   "flight_id": "KE8RES-8_2026-06-20",
   "payload_type": "WSPR",
   "seed_time": "2026-08-16 16:36:00",
   "seed_lat": 69.39583,
   "seed_lon": -41.41667,
   "seed_alt_m": 12260.0,
   "seed_age_h": 0.73,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-23 16:00:00",
    "lat": 65.60421,
    "lon": 131.43274,
    "alt_m": 12089.9
   },
   "member_spread_deg": {
    "lat": 40.26,
    "lon": 181.64
   },
   "member_spread_now_deg": {
    "lat": 0.12,
    "lon": 0.29
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KE9DAB-11",
   "flight_id": "KE9DAB-11_2026-07-29",
   "payload_type": "WSPR",
   "seed_time": "2026-08-13 21:11:00",
   "seed_lat": 63.66667,
   "seed_lon": 161.54167,
   "seed_alt_m": 10970.0,
   "seed_age_h": 68.15,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-23 11:45:00",
    "lat": 44.25709,
    "lon": 1.6632,
    "alt_m": 11184.7
   },
   "member_spread_deg": {
    "lat": 43.71,
    "lon": 149.99
   },
   "member_spread_now_deg": {
    "lat": 22.88,
    "lon": 15.65
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KI6DS-11",
   "flight_id": "KI6DS-11_2026-02-03",
   "payload_type": "WSPR",
   "seed_time": "2026-08-16 09:35:45",
   "seed_lat": 70.24995,
   "seed_lon": 114.29169,
   "seed_alt_m": 13120.0,
   "seed_age_h": 7.74,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-23 11:30:00",
    "lat": 81.26399,
    "lon": -97.71957,
    "alt_m": 13072.8
   },
   "member_spread_deg": {
    "lat": 21.68,
    "lon": 308.26
   },
   "member_spread_now_deg": {
    "lat": 3.58,
    "lon": 0.73
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "SP2ROC-41",
   "flight_id": "SP2ROC-41_2026-01-25",
   "payload_type": "WSPR",
   "seed_time": "2026-08-16 06:36:00",
   "seed_lat": 15.47917,
   "seed_lon": 145.875,
   "seed_alt_m": 16600.0,
   "seed_age_h": 10.73,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-23 11:30:00",
    "lat": 11.98466,
    "lon": 16.52702,
    "alt_m": 16505.7
   },
   "member_spread_deg": {
    "lat": 41.42,
    "lon": 110.58
   },
   "member_spread_now_deg": {
    "lat": 2.21,
    "lon": 4.07
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "SP6MPL-9",
   "flight_id": "SP6MPL-9_2026-08-02",
   "payload_type": "APRS",
   "seed_time": "2026-08-04 04:05:45",
   "seed_lat": 45.52942,
   "seed_lon": 75.286,
   "seed_alt_m": 12836.0,
   "seed_age_h": 301.24,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-23 11:30:00",
    "lat": 45.10873,
    "lon": -127.15068,
    "alt_m": 12933.6
   },
   "member_spread_deg": {
    "lat": 54.44,
    "lon": 315.18
   },
   "member_spread_now_deg": {
    "lat": 31.63,
    "lon": 255.68
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "VE3VRO-36",
   "flight_id": "VE3VRO-36_2026-07-30",
   "payload_type": "WSPR",
   "seed_time": "2026-08-16 06:11:00",
   "seed_lat": 45.33333,
   "seed_lon": 165.0,
   "seed_alt_m": 13400.0,
   "seed_age_h": 11.15,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-23 11:45:00",
    "lat": 48.01308,
    "lon": -50.98136,
    "alt_m": 13363.9
   },
   "member_spread_deg": {
    "lat": 25.27,
    "lon": 105.97
   },
   "member_spread_now_deg": {
    "lat": 0.86,
    "lon": 4.33
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "W0RBO-12",
   "flight_id": "W0RBO-12_2026-05-02",
   "payload_type": "WSPR",
   "seed_time": "2026-08-16 04:20:23",
   "seed_lat": 50.79161,
   "seed_lon": 177.66669,
   "seed_alt_m": 13240.0,
   "seed_age_h": 12.99,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-23 11:45:00",
    "lat": 56.4889,
    "lon": -43.93167,
    "alt_m": 13236.4
   },
   "member_spread_deg": {
    "lat": 41.84,
    "lon": 76.28
   },
   "member_spread_now_deg": {
    "lat": 7.16,
    "lon": 12.91
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "ZS6SRC-37",
   "flight_id": "ZS6SRC-37_2026-07-31",
   "payload_type": "WSPR",
   "seed_time": "2026-08-16 01:39:00",
   "seed_lat": -27.66667,
   "seed_lon": -155.41667,
   "seed_alt_m": 12330.0,
   "seed_age_h": 15.68,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-23 11:45:00",
    "lat": -30.39169,
    "lon": 123.14624,
    "alt_m": 11890.7
   },
   "member_spread_deg": {
    "lat": 14.05,
    "lon": 122.0
   },
   "member_spread_now_deg": {
    "lat": 2.18,
    "lon": 4.82
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "ZS6SRC-39",
   "flight_id": "ZS6SRC-39_2026-08-05",
   "payload_type": "WSPR",
   "seed_time": "2026-08-12 06:21:00",
   "seed_lat": -22.16667,
   "seed_lon": 146.45833,
   "seed_alt_m": 15900.0,
   "seed_age_h": 106.98,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-08-23 11:45:00",
    "lat": -6.60268,
    "lon": -18.8865,
    "alt_m": 15986.9
   },
   "member_spread_deg": {
    "lat": 28.87,
    "lon": 268.12
   },
   "member_spread_now_deg": {
    "lat": 12.29,
    "lon": 333.11
   },
   "display_as": "region",
   "display_reason": "member_spread"
  }
 ]
}